1. Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus of a type wherein a magnetic disk having a magnetic recording layer formed on a rigid substrate is rotatable at a high speed and a magnetic head is disposed on the surface of the disk so that magnetic recording and reproduction are conducted by the head while rotating the disk at a high speed.
2. Discussion of Background
As is well known, in a magnetic recording and reproducing apparatus of this type, a hard magnetic disk comprising a rigid substrate made of aluminum and a thin magnetic layer formed thereon by a method such as a fine magnetic powder coating method, a plating method or a sputtering method, is rotated at a high speed (e.g. 3600 rpm) so as to produce a dynamic pressure between the magnetic disk and a flying magnetic head so that the magnetic head is lifted and floats with a certain flying height by a fine air bearing, while the magnetic recording and reading are conducted.
In order to accomplish high density magnetic recording with a magnetic recording and reproducing apparatus of this type, it is necessary to minimize the flying height of the magnetic head and to reduce the spacing loss. However, if the flying height is lowered to reduce the spacing loss, it tends to be more likely that the magnetic head is susceptible to the influence of the surface condition of the magnetic disk or of the vibration during the high speed rotation and impinges on the surface of the magnetic disk, whereby there will be a problem such as a damage to the magnetic disk or a head crush and the durability tends to be low. To avoid such a problem, it has been common to set the flying height of the magnetic head at a level of from 0.1 to 0.3 .mu.m to secure the durability. Thus, there has been a limitation in the reduction of the spacing loss and accordingly in the improvement for high density magnetic recording.